Possessed Stereo

[HTandB]

Hello all, I'm brand new to the forum and new to BMW products as well. Having said that, I have more than a few decades turning wrenches on automobiles and building them from the ground up, I'm not a stereo guy though. I'm hoping someone here can help me out with my first BMW mystery that maybe isn't a mystery to someone who knows the cars.

I just picked up a fully loaded 2000 750iL at a silly price that I couldn't pass on, the car is in good condition cosmetically and the V12 purrs right along, transmission was rebuilt about 2k miles back. The stereo however is having issues, I am getting a really bad clicking/popping/static from all of the rear speakers; if I fade full front then everything is fine, it's limited to the back 8(?) speakers. I've looked at the amp, CD Changer and other gear in the trunk and made sure the connections are good. I've checked the back of the stereo/Navigation/ tape-player dash unit for connections, they all seem fine. I understand the amps in these can be problematic.

Here's my mystery that's making me feel like little Carol-Ann from poltergeist - I left the stereo on and turned the key off, I removed the stereo head/navagation/ tape unit from the dash (completely removed it, disconnected all wiring and pulled it from the car) and turned the key back on and started the car... and the stereo came back on, same channel it was on before and same volume (same clicking). It literally made me do a double-take looking from the stereo unit sitting outside the car to the empty hole in the dash. I turned the key off and back on again, same result... actually did this several times because it just wasn't registering in my brain. I turned the key off, reinstalled the head unit, turned the key on and then turned the stereo off.

Is the head unit in the dash simply controls for the receiver located somewhere else in the car? If so where is the receiver?

Thanks in advance and feel free to take a few shots because I feel kinda silly asking this... but what am I missing here, I've never pulled a stereo from a car and had it keep playing along...

[ConvGeorge]

Yes, the radio is in the trunk, the thing in the dash is just the controller, display unit and tape source.

[951Dreams]

Hello all, I'm brand new to the forum and new to BMW products as well. Having said that, I have more than a few decades turning wrenches on automobiles and building them from the ground up, I'm not a stereo guy though. I'm hoping someone here can help me out with my first BMW mystery that maybe isn't a mystery to someone who knows the cars.

I just picked up a fully loaded 2000 750iL at a silly price that I couldn't pass on, the car is in good condition cosmetically and the V12 purrs right along, transmission was rebuilt about 2k miles back. The stereo however is having issues, I am getting a really bad clicking/popping/static from all of the rear speakers; if I fade full front then everything is fine, it's limited to the back 8(?) speakers. I've looked at the amp, CD Changer and other gear in the trunk and made sure the connections are good. I've checked the back of the stereo/Navigation/ tape-player dash unit for connections, they all seem fine. I understand the amps in these can be problematic.

Here's my mystery that's making me feel like little Carol-Ann from poltergeist - I left the stereo on and turned the key off, I removed the stereo head/navagation/ tape unit from the dash (completely removed it, disconnected all wiring and pulled it from the car) and turned the key back on and started the car... and the stereo came back on, same channel it was on before and same volume (same clicking). It literally made me do a double-take looking from the stereo unit sitting outside the car to the empty hole in the dash. I turned the key off and back on again, same result... actually did this several times because it just wasn't registering in my brain. I turned the key off, reinstalled the head unit, turned the key on and then turned the stereo off.

Is the head unit in the dash simply controls for the receiver located somewhere else in the car? If so where is the receiver?

Thanks in advance and feel free to take a few shots because I feel kinda silly asking this... but what am I missing here, I've never pulled a stereo from a car and had it keep playing along...

Sell it or burn it... Now! Before it names itself Aldof and starts chasing you around!!!

But seriously I didn't know they would do that, but with the bus in these, I'm not terribly surprised. Almost everything in these talks to some computer modual somewhere that does the actual work. You press a switch, it doesn't do work work itself but alerts a computer somewhere you want something done and the computer handles it.

Yes, it's Skynet's birth. If your last name is Conner, be expecting Arnold soon.

Could the popping be really really blown speakers? Mine were terrible.

Sent from my SM-G965U using Tapatalk

[HTandB]

Yes, the radio is in the trunk, the thing in the dash is just the controller, display unit and tape source.

Thanks, that's what I figured but I'm at a loss as to where the darn thing is mounted. Any idea on specific placement?

I've torn the left side of the trunk apart and the only things left back there are the Utloewe amp, the CD changer and the Navigation system (drive and the reciever); I've removed the motorolla telephone controller and booster.

All of the wires from the Amp run forward through the body and into the passenger compartment

There is nothing mounted behind the panel forward of the amp. (at the wheel well). The batteries of course are on the right side of the trunk and there's nothing forward of them. There is nothing mounted in the spare tire well (except the tire) I even checked under the rear seats. The last two were a bit of a desperation move but I figured I should eliminate any areas I could.

[ConvGeorge]

It's behind the amp (towards the quarter panel,) hidden under a felt flap. It's a standard DIN size unit, just with no faceplate. I would also concur that your problem might just be blown speakers. The rear deck speakers are almost assuredly blown, and the back door woofers are likely, too.

[HTandB]

Thanks, I appreciate the info from both of you. If they are blown then all of the speakers from the b pillars back are bad. I think the popping is from the right door tweeter (? little one at the top of the panel) the rest are all putting out static over the broadcast.

[ConvGeorge]

The radio sends a two channel signal to the amp, which then digitally divides up the signal to all the channels, each speaker has it's own channel on the amp (except the rear deck, I'm pretty sure each channel drives 2 speakers.) So if you've ruled out the speakers, I would guess the amp is the next thing to consider.

[HTandB]

The radio sends a two channel signal to the amp, which then digitally divides up the signal to all the channels, each speaker has it's own channel on the amp (except the rear deck, I'm pretty sure each channel drives 2 speakers.) So if you've ruled out the speakers, I would guess the amp is the next thing to consider.

Ok, so I found the stereo receiver (that thing is really buried) and checked the connections, everything seemed tight and clean.

Pulled a rear door panel and checked the woofer, visually it looked fine, so I removed it and replaced it with a new-in-box speaker I had for a different project in my shop. Same popping and static came through the new speaker; just to be sure I checked it on a different stereo... it's not the speaker.

Looks like replacement amps are available fairly reasonably, I may try a straight component swap

Thanks again for the assistance - Ryan

[HTandB]

Final update on this one, bought a used amp online and swapped it out - that was the problem, rear door speakers are playing clearly now and I think the rear deck are blown but all the static and popping is gone. Thanks for the input, appreciate the help